Why Does My House Smell Like Sewer? Common Causes and Solutions

A sewer smell in your home is more than unpleasant—it can indicate a plumbing problem that needs attention. Here are the most common causes of sewer odors and what you can do about them.

Common Causes of Sewer Smell

1. Dry P-Trap

The P-trap is the curved pipe under your sink that holds water to block sewer gases. If a drain isn’t used regularly (like in a guest bathroom), the water can evaporate and allow gases through.

Fix: Run water in unused drains for 30 seconds every few weeks.

2. Damaged or Missing P-Trap

If running water doesn’t solve the problem, the P-trap may be cracked, corroded, or improperly installed.

Fix: Have a plumber inspect and replace if needed.

3. Blocked Vent Pipe

Plumbing vent pipes allow sewer gases to escape through your roof. If blocked by debris, leaves, or animal nests, gases can back up into your home.

Fix: Have the vent pipe cleared—this usually requires roof access.

4. Cracked Sewer Line

A crack in your sewer line can allow gases to seep into the soil around your home and enter through the foundation.

Fix: Camera inspection to locate the crack, then repair or replacement.

5. Toilet Wax Ring Failure

The wax ring seals the base of your toilet to the drain. If it fails, sewer gases can escape around the toilet base.

Fix: Replace the wax ring—a relatively simple repair.

6. Sewer Backup

If the smell accompanies slow drains or gurgling, you may have a partial sewer backup pushing gases back into your home.

Fix: Professional drain cleaning to clear the blockage.

When to Call a Professional

Call a plumber if:

• The smell persists after running water in all drains
• You notice the smell throughout your home
• The smell accompanies other symptoms (slow drains, gurgling)
• You can’t locate the source

Health Concerns

Sewer gases contain methane and hydrogen sulfide, which can cause headaches, nausea, and dizziness with prolonged exposure. Don’t ignore persistent sewer smells—get them addressed promptly.

Sewer smell in your Bay Area home? Call (415) 555-0123 to find and fix the source.